The purpose of this project is to determine the extent of the peptostreptococcal pupulation in dental plaque from humans and experimental animals at different sites in the mouth. Polyclonal antibodies have been raised against whole cells of both a stock ATCC peptostreptococcal strain and an oral isolate provisionally identified as a petostretococcus. Preliminary results show little cross reactivity with other oral microorganisms and also little strain cross reactivity. The peptostreptococal pupulation of plaque will be examined using fluorescently labelled antibody